Jailbreak

Cydia

Concerns have been raised about Mac App Store security after a simple cut-and-paste workaround was found that defeats copy protection for some paid apps. While many pundits are blaming developers for not following Apple's security guidelines, others are pointing out that the recommendations are complicated and incomplete.

Just hours after apps began appearing on the Mac App Store yesterday, news emerged that you could get around the copy protection on some apps by exchanging the receipt and signature files with ones from a free app. John Gruber of Daring Fireball said the vulnerability was due to poor programming, saying that "it appears that many apps don't perform any validation whatsoever," and urged Apple to "test for this in the review process, and reject paid apps that are susceptible to this simple technique."

However, developer Sean Christmann points out that the guidelines call for apps to validate receipts against plaintext data external to the binary itself, located in the Info.plist file. A much better approach, Christmann suggests, would be to validate against values hard-coded into the app. Christmann noted that the "pastebin" workaround not only allowed users to defeat the admittedly-lax security on Angry Birds, but also another paid app he had copied from a friend's computer, in what he called "a massive failure in the implementation of Apple's receipt system."

Jailbreaking and pirating are two very separate activities that are already too confused in the public's mind, which is why I'm not posting any details about the workaround here. Developers deserve to be paid for their hard work, which is the whole idea behind Cydia as a free market. With pirates gearing up to rip apps off the Mac App Store, developers need to be very cautious to protect their work from unauthorized copying. While following Apple's guidelines is an important first step, efforts can't stop there.